1. Field of the Invention
The invention relates to a fuel cell module.
2. Description of the Related Art
The fuel cell generates electric energy, generally, by using hydrogen and oxygen as fuels. The fuel cell is environment-friendly and is able to achieve high energy efficiency, so that fuel cells are being widely researched and developed as a future energy supply source.
Generally, a fuel cell has a fuel cell stack that is constructed by stacking a plurality of unit cells, and therefore generates large electric power. Japanese Patent Application Publication No. 2007-59377 (JP-A-2007-59377) describes a reformer-integrated type fuel cell in which a reformer is disposed on an upper portion of a fuel cell stack. In this technology, oxidant gas flows in a reactant gas distributing member, and is thereby supplied to a lower end of each unit cell.
In contrast, according to the technology described in JP-A-2007-59377, in the fuel cell stack in which a plurality of unit cells are stacked, the amount of heat dissipation varies between unit cells located at a central portion of the fuel cell stack in the cell stack direction and unit cells located in at end portions of the fuel cell stack in the stack direction. Therefore, difference in temperature in the fuel cell stack in the stack direction, that is the temperature is relatively high in a central portion, and relatively low in end portions may occur. If such a temperature difference occurs within the fuel cell stack, the electricity generation efficiency may decline.